Residual renal function is beneficial for adequacy of haemodialysis, quality of life and mortality in dialysis patients. Our prospective randomised investigation aimed to analyse the effects of the microbiological quality of dialysis fluid on the course of residual renal function after initiation of haemodialysis. Thirty patients starting haemodialysis were randomly assigned to ultrapure or conventional dialysate. During the 24-month study period, creatinine clearance, CRP and IL-6 levels, hydration status, number of hypotensive episodes and blood pressure recordings were assessed every 6 months. Residual renal function declined in both groups during the study period, although there were no statistically significant differences in demographic (age, gender), renal (cause of end-stage renal disease, residual renal function, hypertension, ACE inhibitors) and treatment characteristics (Kt/V urea) at recruitment. The use of mildly contaminated (up to 300 CFU/ml) dialysate resulted in higher CRP and IL-6 levels and more pronounced loss of residual renal function. Multiple regression analysis showed that the microbiological quality of the dialysate is an independent determinant of the loss of residual renal function. Ultrapure dialysis fluid combined with high-flux synthetic membranes are effective components of renal replacement therapy to slow the loss of residual renal function in haemodialysis patients. These improvements of haemodialysis are desirable, but add to treatment costs.
